This research aims to examine certain statistical properties of the design and analysis of cancer clinical trials in order to consider planned interim analysis of several endpoints simultaneously and to develop more generally applicable statistical methodology for such trials. The Specific Aims are: to propose new statistics for the design and analysis of cancer clinical trials which are based on more than one endpoint, including right censored (lifetime) endpoints, and to assess the operating characteristics of those statistics; to develop new group sequential designs for cancer clinical trials, including use of multiple endpoint statistics; to extend group sequential methods to k-(greater than two) armed trials, first with a single endpoint, then with multiple endpoints and then to more complicated experimental designs; to investigate the applicability to cancer clinical trials of other approaches to the "multiplicity problem"; and to evaluate the new methods by comparing them with other available methods using current clinical trial data as well as simulated data. The intent is to produce a variety of realistic strategies for the conduct of cancer clinical trials in order to facilitate and make more efficient the evaluation of new cancer treatments. The methods developed will continue to be both theoretical and numerical and will be applied both prospectively and retrospectively to the analysis of cancer clinical trials, at Memorial Sloan-Kettering Cancer Center. The intent is to produce a variety of realistic strategies for the conduct of cancer clinical trials in order to facilitate and make more efficient the evaluation of new cancer treatments.